Python script to list tables those doesn't have primary key constraint in all postgres databases

I have around 200 postgres databases in aws rds across all accounts. I have two metadata tables which has connection info and credentials info. Tasks: 1. Need to use these two tables to make a connection string to connect every database. 2. loop over every database, connect and list tables those doesn't have primary key. If a table doesn't have primary key, get estimated number of rows from table statistics. 3. have the script create a table in local database with columns like account,region,inst_id,schema,table,estimated_rows. 4. store the results from step 2 in step 3 table.